Combustion apparatus



JuEy 24, 1934. w. B. CHAPMAN COMBUSTION APPARATUS Filed Feb. 23, 1929 2 Sheets-Sheet 1 RINVENTOR Q04 ATTORNEYS Jhmlly 24, 1934.. w. B. CHAPMAN COMBUSTION APPARATUS Filed Feb. 23, 1929 2 Sheets-Sheet 2 zlllllllllllllllllmlfllllllllfllr 4 m mun! Q IN EN OR P at A51 ATTORN EYS @atented July 24 19334 UNHTED STATES retract The invention relates to combustion apparatus employing a solid firebecl and particularly a rlre= bed of such thickness as to generate producer gas. One important object of the invention is to provide in connection with afirebed oi the above type, means for adequately mixing with the gases ris""g from the surface of the :drebed secondary at or completing combustion. This feature of tire invention is particularly important where ebeds of large area are employed, under which conditions it is increasingly difficult to inject secondary nto the gas produced in the the bed, in such manner as to'secure a fairly uniform mixture or the air and gas, over all points of the Another object of the invention when applied to firebecls of the unclerieecl type is to promote the uniform feed disti ution oi the fuel over the irebed by moving fuel from the tightly packed zone in the center of the into the loosely paclred zone near the walls of the In accordance with one :ieatiue of tlie'invention I employ secondary feeding which is located centrally of to e and substan-= tially at its siu'iace, and which thus CODflIlES the gases rising from the nrebed to an annular path of travel surrounding each member, thereby analz= ing it possible to project air outwardly from such member into the annular rising column or gas in such manner tlie air mixes unifor J and in proper quanti es therewith at substantially all points around tlie periphery of the fuebcd. Toe admission of secondary air in the above manner into an annular column of rising gas produces conditions under which at all points around the firebed the distance which the secondary mr has to travel in order to penetrate and mix thoroughly with the gas is not so large as to require undue blast pressure or destroy the desired uniformity of mixture which is necessary for complete cornbustion, without supplying any undesirable excess of air. This secondary air supply member may also be rotated and constructed in such a mom nor as to promote uniform ruel distribution over the firebed.

Further objects and advantages of the inven= tion will be in part obvious and in part specifically pointed out in the description hereinafter contained which, taken in conjunction with the accompanying drawings, discloses a preferred em bodiment thereof. Such embodiment, however, is to be considered merely as illustrative oi its principles. In the drawings Fig. l is a central vertical section through a ((Cl. Mil-=45) combustion apparatus constructed to operate in accordance with the invention.

Fig. 2 is a perspective view showing detached the central upstanding conduit or post which leads upwardly to a secondary air supplying mem ber hereinafter described, said view also sh0wing (with the lower part thereof cut away) a fuel feeding column surrounding the above mentioned conduit.

Fig. 3 is a transverse section taken on the broken line 33 of Fig. 1, looking in the direction of the arrows.

Fig. l is a perspective view showing detached one of the blades working in the ash bed as acre inaiter described.

Fig. 5 is a transverse section taken on line 5-5 of Fi 1 looking in the direction or the arrows.

The invention is disclosed as applied to a conn bustion apparatus having stationary cylindrical sidewalls adapted to enclose the lirebed, the lower portion 1 or such sidewalls being shown as water cooled and resting upon a suitable number or pedestals 2 which extend up from the floor. As indicated on the drawings, the top of tire iuel bed will usually be up somewhere the level of the top of the water cooled sidewall section 1, since the invention contemplates the use or fire beds thicker those ordinarily employed where complete combustion is desired, in order that the air which passes through the firebecl as hereinafter described, causes combustible gases to be given off at the top of the firebed, instead of producing complete combustion. The oi the ash bed will usually lie at about the level indicated in mg. l.

The fuel and ash beds are preferably supported from underneath by a stationary annular supporting member 3 illustrated as resting upon a central collar l, and surrounding a stationary tuyere hood 5 which latter rests upon a hollow column 6 enclosed by the collar 4 above inen= tioned and spaced therefrom so as to provide an annular primary air intake passageway 71 leading out into the ash bed under tuyere 5 at its top, and communicating at its bottom with the primary air supply pipe 8. V

A water seal is preferably provided atthe bottom of the ash bed, as by means of a rotary pan 9 which underlies the firebed supporting member 3 above mentioned, and surrounds an annular skirt to which projects down from the water cooled sidewall section 1 above described. This pan 9 may be rotated in any suitable manner, for example, by the plunger 90. (Fig. 3) of a CIT- ram which engages teeth 9b on the periphery of the pan. In order to agitate the firebed from underneath through the medium of the ash, break up clinkers and assist in the removal of the ash, I prefer to provide a suitable number of agitating members 11 and 12, which are supported upon rotary pan 9 and project through the annular ash discharge opening 13 between the supporting member 3 and skirt 10, into the interior of the furnace, and rotate with pan 9. The agitating members 11 produce a radial wave motion in the firebed which extends well up into the firebed and by closing the blow-holes tends to maintain uniform conditions of gas production therein. These members are also slightly outstroking in their action so as to push a certain amount of ash outwardly through the annular opening 13 into the outer part of pan 9, from which latter the ash may be removed in known manner (not shown).

The agitating members 12 tend to break up clinker in the region of skirt 10, just above the ash discharge opening 13, or to lift up any clinker not so broken up so as not to obstruct the ash discharge opening. As shown, the skirt 10 is preferably provided with inclined ribs 14, to cooperate with the agitating members 12 in breaking up the clinker.

I prefer to utilize the invention in connection with a firebed of the underfeed type, the fuel being fed in the illustrated form of the invention from a hopper 15 to a feed screw 16, which forces the fuel through a pipe 1'7 extending into the central part of the apparatus and communicating at its delivery end with the space around a rotary upstanding hollow column 18 enclosed by the hollow column 6, and provided with a spiral fin 19, which forces the fuel upwardly into the central portion of the firebed.

In accordance with the present invention, I provide for the central portion of the firebed a secondary air supply member 20, which projects secondary air into the combustible gases as they rise from the surface of the firebed, and may also perform certain other functions as hereinafter described. In the illustrated form of the invention this secondary air supply member is approximately in the shape of an inverted bell or mushroom, and is connected to the upper end of a hollow post 21 enclosed by the rotary column 18, and receiving secondary air through a. pipe 22 leading into the lower end of the latter, the member 20 being hollow and provided with a series of nozzles 23 in its peripheral wall, which are preferably directed somewhat tangentially as indicated in Fig. 3.

I prefer to rotate the secondary air supply member 20, which may be done by driving it from column 18, and if desired it may be made adjustable in height so as to lie at all times approximately on the surface of the firebed in case different heights of firebed are employed. As shown (Fig. 1) the column 18 is provided with an internal inclined lug 24, which engages in an inclined or spiral groove 25 in post 21, with the result that as column 18 rotates, it carries the secondary air supply member along with it at constant height, so long as the weight of such member and its resistance to turning is balanced against the upward thrust imparted by lug 24; but if the firebed should become shallower, member 20 will drop down correspondingly by gravity, or if the thickness of the firebed should increase, tending to bury the member 20 in it and thereby increase its torsional resistance, the lug 24 will raise up the member 20 until a balance of the resultant forces is again reached by such member coming to the surface of the firebed. Preferably a device is employed to regulate the fuel feed automatically with regard to the level of the secondary air-supply member. As shown a rod 26 is supported in axial position from the post 21 and has stops 2'? and 27 at its lower end adapted to engage the pivoted arm 28 of an electric switch shown diagrammatically as including a fixed contact sector 29 having a regulating resistance and a movable contact 30, interposed in the supply circuit 31, which latter may be understood as connected to a motor 32 for driving the rotary fuel feeding parts of the apparatus. As the secondary air supply member rises above a predetermined level, the rate of fuel fed is gradually reduced and finally may be entirely cut off and conversely as the secondary air-supply member falls below a predetermined level the rate of fuel feed is gradually increased until the maximum rate is reached. Usually the fire-bed will be kept automatically at a height near the maximum in order that the mass of burning fuel may be sufiicient to respond quickly to sudden overloads.

To assist in cleaning the outer surface of post 21, thereby enabling the latter to move up and down as required within column 18, the upper end of such column may be provided with interior lugs 32, (Fig. 2) and upwardly extended fingers 33, adapted to scrape off any deposits on the post 21, Whenever relative movement occurs between the latter and the column 18.

In the operation of the apparatus, the fuel will be fed upwardly from beneath into the central portion of the fire-bed around post 21. and the fuel will tend to travel upwardly to the central part of the top portion of the fire-bed until it is thick enough to make combustible gas and is deflected radially outwardly by the bottom wall of the member 20, the latter therefore serving as a fuel distributing or deflecting member to prevent the fresh fuel from piling up in a conical mound in the central portion of the fire-bed. To assist in performing the above function, the member 20 may be provided on its under side with ribs 34, which tend to push the fuel toward the outer peripheral part of the fire-bed.

Primary air will be fed through tuyere hood 5 to the bottom of the firebed in sufficient quantity to produce the required amount of combustible gas of the producer gas type to heat a boiler, for example, as required. The uniform conditions of gasification which will be maintained in the firebed due to its symmetrical fuel feed, symmetrical ash discharge, and thorough agitation, etc., make it possible to obtain a uniform grade of gas, which is necessary in order to avoid using a large excess of secondary air over what would be theoretically sufficient for complete combustion.

As the combustible gases thus produced rise from the surface of the fuel bed, they are met by the jets of secondary air passing out from nozzles 23 in member 20, whereby a combustible mixture of air and gas is formed which then burns in the space above the firebed. It will be noted that the member 20 obstructs the upward passage of gas from a substantial proportion of the fuel 'bed (i. e. the central portion) thereby confining the upwardly traveling combustible gases to the zone surrounding member 20, in which zone the secondary air may be intimately and uniformly mixed therewith. The above feature is particularly useful with firebeds of large diameter, in regard to which it is difficult to mix secondary air uniformly with the combustible gaseson account of the great distances to be penetrated by the incoming air.

For still larger diameters, additional secondary or tertiary air may be also admitted to the space above the firebed in order that the rising column of gas may be completely penetrated, as by means of an .annular series of air inlet openings 35 in the sidewall of the furnace above the water cooled section 1, and leading from an annular chamber 36, to which a tertiary air supply pipe 37 is connected. These openings also are preferably directed somewhat tangentially in order to promote a thorough mixture of the air with the rising burning gases, and if said openings are employed in conjunction with secondary air supplied through member 20, only approximately enough tertiary air will be admitted to insure complete combustion. If desired, with firebeds ofmoderate diameter, all of the secondary air may be admitted through the openings 35, the member 20 suitably cooled serving to confine the rising combustible gases to the annular space between it and the enclosing walls, whereby the secondary air may penetrate the gases to better advantage.

As illustrated the top and outside surfaces of member 20 may be formed of suitable refractory or heat-resistant material, to prevent injury due to the high temperature in the combustion chamber, such member, however, being largely aircooled by the passage of secondary air therethrough and being protected by the fresh incoming fuel in respect to its lower surfaces. The firebed agitating members 11 and 12 and other parts beneath the ash bed, will be sufficiently cooled by the water carried in pan 9, while the lower section 1 of the sidewall, as above stated, may also be water cooled. As indicated on the left of Fig. 1, a steam pipe 38 may lead from the upper part of the water jacket of sidewall section 1, to some suitable point in the primary air supply, so as to pass a certain amount of steam into the firebed along with the primary air.

While a specific embodiment of the invention has been disclosed it will be obvious that many changes may be made therein without departing from its principles as set forth in the appended claims.

I'claim:

1. A combustion apparatus comprising a gas producer having sidewalls of such height as to be capable of enclosing a firebed of the gas producing type, means for admitting primary air to the lower portion of such a firebed to generate combustible gas therein, means located over the central portion of said firebed and near the surface thereof, for projecting secondary air across the path of travel of the gases which rise from the firebed, a secondary air conduit rising up through the firebed from underneath and connected to said last mentioned means, a fuel feeding device of the underfeed type operating concentrically around said conduit, and means connecting said conduit and fuel feeding device for simultaneous rotation.

2. A combustion apparatus comprising a gas producer having sidewalls of such height as to be capable of enclosing a firebed of the gas producing type, means for admitting primary air to the lower portion of such a firebed to generate combustible gas therein, means located over the central portion of said firebed and near the surface thereof, for projecting secondary air across the path of travel of the gases which rise from the firebed, a secondary air conduit rising up through the firebed from underneath and connected to said last mentioned means, a fuel feeding device of the underfeed type operating concentrically around said conduit, and means connecting said conduit and fuel feeding device for simultaneous rotation but permitting said conduit to move vertically with respect thereto.

3. A combustion apparatus comprising a gas producer having sidewalls adapted to enclose a firebed, means for admitting primary air to the lower portion of such a firebed to generate combustible gas therein, means located over the central portion of said firebed and near the surface thereof, for projecting secondary 'air across the path of travel of the gases which rise from the firebed, said means being automatically adjustable in height to conform to different heights of firebeds, means for feeding fuel upwardly into the firebed from beneath, said last mentioned means being located under said secondary air projecting means.

4. A combustion apparatus comprising a gas producer having sidewalls adapted to enclose a firebed, means for admitting primary air to the lower portion of such a firebed to generate combustible gas therein, means located over the central portion of said firebed and near the surface thereof, for projecting secondary air across the path of travel of the gases which rise from the firebed, said means being automatically adjustable in height to conform to different heights of firebeds, a fuel feeding device for said firebed and means for automatically stopping said fuel feeding device when the height of said secondary air projecting means exceeds a given limit.

5. A combustion apparatus comprising a gas producer having sidewalls adapted to enclose a firebed, a fuel feeding device located centrally with regard to said walls for feeding fuel upwardly into said firebed from beneath, a member disposed centrally upon the central portion of the firebed to deflect the fuel out radially over the firebed, means being provided whereby the position of said member is automatically adjusted to conform to different heights of firebed.

6. A combustion apparatus comprising a gas producer having sidewalls adapted to enclose a firebed, means for admitting primary air to the lower portion of such a firebed to generate corn bustible gas therein, means located over the central portion of said firebed and near the surface thereof, for projecting secondary air across the path of travel of the gases which rise from the firebed, a fuel feeding device of the underfeed type operating concentrically with respect to said secondary air projecting means, and means acting automatically to regulate the height of said secondary air projecting member in accordance with the height of the firebed.

WILLIAM B. CHAPMAN. 

